High reactance transformer



March 28,1950 w. FOERSTE 2,502,083

HIGH REACTANCE TRANSFORMER Filed July C50, 1945 3 Sheets-Sheet 1 IN V EN TOR. Mu. IA M Foe/957's March 28, 1950 w. E T 2,502,083

HIGH REACTANCE TRANSFORMER Filed July 30, 1945 3 Sheets-Sheet 2 1M EN TOR. lV/LL/AM FOf/P 75 A T TOR/VEY March 28, 1950 w. FOERSTE 2,502,083

HIGH REACTANCE TRANSFORMER Filed July 30, 1945 5 Sheets-Sheet 3 IN V EN TOR. IV/LL /AM FOE/Q5 TE by Z Z Patented Mar. '28, 1950 HIGH REACTANCE TRAN SFORMEB William Foerste, Pelham Manor, N. Y.; Am Kane, administratrix of said William Foerste,

, deceased, assignor of one-half to Eugene A.

Quarrie, Scarsdale, N. Y.

ApplicationJuly 30, 1945,. Serial No. 607,747

11 Claims. ,(Cl. 323-61) The invention relates to high reactance, magnetic leakage transformers suited, for example,

to the operation of rectifiers such as the gas-filled or oxide types, variable speed motors, gas-filled lamps of the ordinary luminescent or fluorescent types, germicidal and ultra-violet lamps, etc.

Regulation of the output'of transformers of this nature is attempted, as a rule, by including in circuit with the primary or the secondary of the operating transformer large value impedance, or variable voltage supply devices, which increase the cost of and reduce the voltage applied by the transformer. Such expedients result, generally, also in inefficient, unsatisfactory and unstable operation of the apparatus connected with the transformer.

The present application is a continuation-inpart of my application Serial No. 412,492, filed September 26, 1941, which has matured into U. S. Letters Patent No. 2,392,845, dated January 15, 1946.

It is an object of the instant application to provide a transformer of high reactance which will develop the required high initial potential and at the same time allow for variations in the output of its secondary through control of its primary circuit or of its secondary circuit for the operation of the hereinbefore-noted apparatus.

A further object of the invention is to provide a transformer which will be particularly suitable for the operation of a luminescent tube at different intensities of illumination.

A still further object of the invention is to provide a transformer of the aforesaid type having its primary and secondary windings in autotransformer relationship.

Another object of the invention is to include in the transformer permanently effective means, aside from the variable control, for preventing an overload.

Still another object of the invention is to provide a simple and rugged construction of transformer by embodying the control features as an netic relationship. This reactor is magnetically positioned between said primary and secondary, and is separated from the core by a non-magnetic gap for shunting from said secondary a portion of the flux generated by the said primary. It 65 includes a coil for controlling the load of said single primary or secondary windings, means being provided, also, whereby said reactor coil may be connected alternatively to one of the said windings, as in series with the secondary winding, or the primary winding may be connected in series with the coil or, alternatively, the primary directly to a source of electrical energy, and likewise the secondary winding. In addition, a plurality of taps may be taken from the reactor coil, which taps may be selectively connected by the aforesaid means in series with a particular transformer winding.

The reactor may be provided, also, with an additional coil which is arranged to be retained permanently in series with a primary or a secondary winding to prevent overload therein.

The nature of the invention, however, will best be understood when described in connection with the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of the novel transformer with control arrangement, having primary and secondary windings in auto-transformer relationship; and is shown, by way of example, connected to a luminescent lamp for operation thereof at different intensities of illumination.

Fig. 2 is a similar view illustrating a modification.

Fig. 3 is a diagrammatic view illustrating the provision of overload-prevention means in the novel transformer.

Fig. 4 is a view similar to Fig. 1 but with the primary and secondary windings in the conventional separated relationship, and the control effected through the secondary winding.

Fig. 5 illustrates a transformer of the nature shown in Fig. 4 with provision of overload-prevention means.

Referring to the drawings, more particularly Fig. 1 thereof, l0 designates the closed core construction of the novel transformer, which may be effected in the usual manner of laminated iron, said core affording a closed magnetic circuit. The primary winding H and the secondary winding l2 are shown as arranged in auto-transformer relationship, and power is derived from a supply main through a lead l3 and through a switch I4 connected with a lead l3. The terminals 15 of the auto-transformer supply power at a substantially constant open-circuit voltage to an adjustable load which may be of relatively low operating voltage, for example, as in the case of loads such as are encountered in the operation of gas-filled lamps of the ordinary luminescent type or of the fluorescent type. Thus, they are shown, by way of example, as connected directly to the electrodes l8 and Il, either of the hot or cold type, of a luminescent lamp including a transparent envelope l8. Winding I2 is thus in inductive relationship to the primary, being coupled as closely as possible thereto, and supplies the lamp with the requisite voltage for its proper operation.

In the operation of 'these lamps, it is under-- stood that an initially high voltage must be supplied by the secondary to effect the ionization of the rare gas in the envelope, this voltage dropping then to a much lower sustaining or working voltage when the lamp is in service or during one-half cycle of operation. The novel arrangement set forth, however, aflords at the same time a ballast to prevent overheating of the tube and disintegration of the tube elements, thereby maintaining the current density and the light intensity.

In accordance with the invention, an auxiliarycore is associated in single-acting shunt magnetic relationship with the core, for example, extending within the main core structure, as shown, to afford a high leakage reactance element or magnetic shunt separated from the core by a non-magnetic gap, and serving to shunt from the secondary I2 a portion of the flux generated by the said primary II. There is provided over the said auxiliary core 20 a winding control for the primary load, and the said winding is divided, for example, into two coil portions 2| and 22. As shown, the winding is divided, preferably, midway to this end by connection of the lead or intermediate tap 23 which extends to a contact point 24. Respective leads 25 and 28 connect the terminals 2! and 28 of the reactor winding to contact points 29 and 30, respectively. By engagement of the switch-arm l4 with these contact points, the entire winding on the auxiliary core or a coil portion may be connected in circuit with the auto-transformer, or the latter may be connected without any ,winding in circuit by setting the switch-arm on the switch-point 29. In the latter instance, the transformer will operate in the usual manner with core 20 introducing a certain amount of reactance due to the normal magnetic leakage providedthereby. However, the amount of this reactance may be respectively increased or decreased accordingly as the winding is energized by setting the switch-arm to switch-point 30 or to switch-point 24, respectively. It will be noted that the secondary winding l2 remains in series relationship to the reactor coil portions so that a control is effected additionally in this respect.

The magnitude of the flux of the said auxiliary core 20 may thus be varied and while this will accordingly vary the current supplied by the secondary, the open-circuit voltage delivered by the said secondary remains substantially constant in accordance with the requirements of the lamp and the relationship between the number of primary and secondary turns. The dimensions of the core, more especially its length, will be according to the requirements of the variation desired and the core may be omitted entirely in some instances and merely the solenoid utilized. The leakage effect of the auxiliary core will then, of course, be missing and only the solenoid is effective to provide for leakage and in accordance with the current flowing in the primary winding.

As illustrated in Fig. 2, a modified form of the novel transformer construction is shown wherein the primary winding 35 is associated in autotransformer relationship with a divided secondary having the separated winding portions 36 and 31 on the closed core structure 38, Primary winding 35 is fed from the power main through leads 39 and 40 to energize the secondary portions which, in turn, afford the supply current to energize a lamp 4|. A condenser 42 across the said secondary portions improves the power factor, as well as facilitating starting; and .the inductance of the secondary tends to prevent disintegration of lamp electrode coating.

A switch-arm 43, when positioned on the switch-point 44, efl'ects the direct connection of main 3940 with the primary 35, other switchpoints 45 and 46 being provided for aflording different current values as set up in the secondary winding 36-41. 'For example, two auxiliary cores 4'! and 48, afl'ording high leakage reactance, are provided with corresponding windings 49 and 50, respectively. One terminal of the former winding is connected to the switch-point 46, the other terminal of said winding being connected by a lead H with the switch-point 45. This lead- 5| is also connected with one terminal of the winding 50, the other terminal of which is connected by a lead 52 with the switch-point 44. When the switch-arm 43 is positioned on switchpoint 45, only the winding 50 will be effective to alter the secondary output; whereas, when located on the switch-point 46, both windings 49 and 50 will be included in series with the primary winding 35. If the windings 49 and 50 be arranged such that the direction of flow will effect magnetization of the respective cores in opposition to the leakage eifects, a regulating effect on the lamp supply current results which prevents overheating and resultant destruction of said'lamp.

A further modification of the auto-transformer output stage shunt control is shown in Fig. 3 in which there is disclosed an overload-preventative means associated with the reactor portion of the transformer. The primary winding 60 and the secondary winding 6| are provided on the closed magnetic core with leads 62 and 63 feeding the transformer, the output of which is connected to a luminescent lamp 54, by way of example. An auxiliary core 65 is associated in single-acting shunt magnetic relationship with the core, for example, extending within the main core structure as shown to afford a high leakage reactance element or magnetic shunt separated from the core by a non-magnetic gap, and serving to shunt from the secondary winding 6| a portion of the flux generated by the said primary 60. There is provided over the said auxiliary core 65 a winding control 56 for the primary load, and the said winding is divided, for example, into a plurality of coil portions which are adaptedvto be connected to the respective switch-points adapted for engagement by a switch arm 61. By engagement of the said switch-arm 61 with these points, the diiferent windings on the auxiliary core may be connected individually in circuit with the autotransformer, or the latter may be connected without any of the coils in circuit by setting the switch-arm on the appropriate switch-point. In this instance, the transformer will operate in the usual manner with the core introducing a certain amount of reactance due to the normal magnetic leakage provided thereby.

In addition to the coil portions, there is pronew with the primary 6!. This coil or winding ll controls the primary overload so that the current passing through the primary'is limited to a predetermined value. Thus, with the switcharm on the particular point II which eliminates all of the coil portions of winding control 66, only the further winding Ill will be in circuit with the primary. This connection, if the direction of winding be chosen accordingly, will set up magnetic flux which aids the leakage effect of the reactor as a whole. It becomes possible, therefore, also to increase the gap between reactor 65 and the closed magnetic core, resulting in less loss of secondary open-circuit voltage.

Such overload-preventative coil as well as the tapped winding for output control is not confined to connection through the primary winding for the regulation to be efiected, but may also be associated solely with the secondary winding. For

example, as indicated in Fig. 4, there is similarly associated with a closed core structure 15, having the primary l6 and a pair of secondary windings I1 and I8 thereon, an auxiliary core 19 in singleacting shunt magnetic relationship. The winding control 80, however, is in this embodiment arranged to be connected in series with one of the secondary windings, as the winding 11, in the provision of switching means embodying the contact points ill, 82, and 83 and a movable switcharm 84 adapted to engage the same to complete series connections with the said secondary, as follows: When the said arm is on the point ill, the entire coil 80 will be included in series with secondary 11; when on the point 82, only the tapped portion; and when on the point 83,the coil will be excluded entirely and the secondary will be connected directly to the lamp 85 and be unaffected by any control other than that due to normal leakage effect of the auxiliary core 19. With the secondary 18 magnetically located as shown, it will be understood that no control thereof will be effected by the aforesaid control means, the secondary 18 permitting constant intensity of illumination of the lamp 86 connected thereto with variable intensity of illumination of the lamp 85 controlled by the secondary 11.

In placing the reactor coil in series with the secondary rather than in series with the primary, constant secondary voltage is insured at all load controls afforded by the reactor coil, for it will be appreciated that when the said reactor coil is in series with the primary, the primary excitation load, though relatively small, may increase the no-load (secondary) effect to an undesirable degree, especially when the reactor coil includes a large number of turns.

Similarly, the foregoing arrangement lends itself to the introduction of overload-preventative means. Reference being had to Fig. 5 of the drawings, 90 designates the closed magnetic core with primary 9| and secondary 92 wound thereon. Intermediate these windings in single-acting shunt magnetic relationship thereto is located the auxiliary core 93 extending, for example, within the main core structure and separated therefrom by a non-magnetic gap. An additional secondary 94, for constant intensity of illumination of a lamp 95, may also be provided on the core!!! as in the case of the embodiment shown in Fig. 4.

To provide the overload-prevention means there is included on the auxiliary core 93, in addition to the tapped control winding 96, a further winding 91 which is permanently connected in series with the secondary 92, through the switch-arm 98 and any of'the contact points 88. This coil or winding 01 controls directly the secondary load and, therefore, indirectly the primary load so that the current passing through said secondary and/or primary is limited to a predetermined value.-

I claim:

1. A current-regulating means for apparatus operating at substantially constant open-circuit voltage, comprising a transformer having a closed, low-reluctance magnetic core, only one primary winding and at least one secondary winding; high reluctance variable reactor means in single-acting shunt magnetic relationship with said core, and including a coil; and switchin means for connecting the reactor in series alternatively to one of the transformer windings or the latter directly to a source of electrical energy supply to vary the current delivered, said reactor means being magnetically positioned between the said primary and secondary windings and separated from the core by a non-magnetic g-ap'to invite magnetic leakage from a portion of said core.

2. The transformer of claim 1, wherein the reactor coil is provided with a plurality of taps, and a switching means is provided for connecting the reactor coil alternatively in series with one of the transformer windings or the latter in series with a selected tap of said reactor coil.

3. The transformer of claim 1, wherein switching means are provided for connecting the reactor coil alternatively to the secondary winding or the latter directly to a source of electrical energy supply.

4. The transformer of claim 1, wherein the reactor coil is provided with a plurality of taps, and a switching means is provided for connecting the reactor coil alternatively in series with said secondary winding or the latter in series with a selected tap of said reactor coil.

5. The transformer of claim 1, wherein an additional coil is provided on the reactor means and is adapted for connection permanently with one of the said windings.

6. The transformer of claim 1, wherein the reactor coil is provided with a plurality of taps, a switching means is provided for connecting the reactor coil alternatively in series with one of the transformer windings or the latter in series with a selected tap of said reactor coil, and an additional coil is provided on the reactor means and is permanently connected in series with one of the said windings through the said switching means.

7. The transformer of claim 1, wherein the reactor coil is provided with a plurality of taps, a switching means is provided for connecting the reactor coilalternatively in series with the secondary winding or the latter in series with a selected tap of said reactor coil, and an additional coil is provided on the reactor means and is permanently connected in series with the said secondary winding through the said switching means.

8. A current-regulating means for apparatus operating at substantially constant open-circuit voltage, comprising a transformer having a closed magnetic core, primary and secondary windings thereon in auto-transformer relationship, high reluctance variable reactor means in single-acting shunt magnetic relationship with said core, magnetically positioned between the primary and secondary windings and separated from the core by a non-magnetic gap to invite magnetic leakage and to direct flux from a portion of the core,

said reactor means including a coil for controlling the load of said auto-transformer.

9. A current-regulating means for apparatus operating at substantially constant open-circuit voltage, comprising a transformer having a closed magnetic core, primary and secondary windings thereon in auto-transformer relationship, high reluctance variable reactor means in single-acting shunt magnetic relationship with said core, magnetically positioned between the primary and secondary windings and separated from the core by a non-magnetic gap to invite magnetic leakage and to direct flux from a portion of the core, said reactor means including a coil for controlling the load of said auto-transformer, the said coil being connected to at least one end of one of the transformer windings.

10. A current-regulating means for apparatus operating at substantially constant open-circuit voltage, comprising a transformer having a closed magnetic core, primary and secondary windings thereon in auto-transformer relationship, high reluctance variable reactor means in single-acting shunt magnetic relationship with said core, magnetically positioned between the primary and secondary windings and separated from the core by a non-magnetic gap to invite magnetic leakage and to direct flux from a portion of the core, said reactor means including. a coil for controlling the load of said auto-transformer, the said coil being connected to both of the transformer windings.

11. A current-regulating means for apparatus operating at substantially constant open-circuit voltage, comprising a transformer having a closed magnetic core, only one primary winding and a divided secondary winding in auto-transformer relationship with said primary winding; a pair of high reluctance variable reactor means respectively in single-acting shunt magnetic relationship with said core, and each including a coil adapted for series connection with both of the windings, said reactor means being magnetically positioned between the said primary winding and the respective secondary sections and separated from the core by a non-magnetic gap to invite magnetic leakage from portions of said core.

WILIJAM FOERSTE.

REFERENCES CITED The following references are of record in the file of this patent:

UNiTED STATES PATENTS 

